This invention relates to a building having an electromagnetic shield structure well-suited for application to an information network system utilizing electric waves, and more particularly to an electromagnetic shield structure for shielding electromagnetic waves at a window opening of a building.
In many modern buildings, information generally is communicated between the interior and the outside of the building by making joint use of information communicating equipment such as multiple electronic exchanges and computers. With the increasing value of information, diversification of user needs and increasingly individual nature thereof, the amount of information involved in such communication is growing. Under these circumstances, how to transmit the necessary information rapidly and at low cost where large-scale buildings are involved has become of prime importance. In an effort to satisfy this need, data highway-type information networks utilizing optical fiber cables or coaxial cables have been studied and proposed.
However, with a data highway system utilizing optical fiber cables or coaxial cables, the cables must be stretched throughout all parts of the building to reach the various pieces of communication equipment, and it is necessary to provide follower ducts or a double-floored structure in order to install the cables. The time needed to complete the work and the expenses involved are significant.
If electric waves are used to transmit information within the building, laying cables is unnecessary but radio law limits the usable frequency to no more than 3 T(tera) Hz owing to the emission of electrical noise waves from such a building. Another problem is that the communication system may malfunction due to electric waves or the like from outside the building.
Accordingly, in a building of the above type, some expedient must be adopted to deal with these elecelectric waves at the window openings, entrances and exits of the building. At the window openings, for example, a mesh or some other electrically conductive material can be used in the window glass to form an electromagnetic shield in the window. However, this necessitates that the window glass mesh and window frame be reliably grounded. To accomplish this, it is necessary that the window glass be electrically connected to the window frame, and that the window frame be electrically connected to the body of the building, e.g. to a grounded part of the building structure such as the iron reinforcing rods in the building concrete. However, the amount of work involved to electrically interconnect all of the window glass panes, window frames and building body is enormous, especially for large buildings and a large number of windows.